writeNewConfig filename packages = do
hPutStr stdout "Writing new package config file... "
createDirectoryIfMissing True $ takeDirectory filename
- h <- openFile filename WriteMode `catch` \e ->
- if isPermissionError e
- then die (filename ++ ": you don't have permission to modify this file")
- else ioError e
let shown = concat $ intersperse ",\n "
$ map (show . convertPackageInfoOut) packages
fileContents = "[" ++ shown ++ "\n]"
- hPutStrLn h fileContents
- hClose h
+ writeFileAtomic filename fileContents
+ `catch` \e ->
+ if isPermissionError e
+ then die (filename ++ ": you don't have permission to modify this file")
+ else ioError e
hPutStrLn stdout "done."
-savingOldConfig :: FilePath -> IO () -> IO ()
-savingOldConfig filename io = Exception.block $ do
- hPutStr stdout "Saving old package config file... "
- -- mv rather than cp because we've already done an hGetContents
- -- on this file so we won't be able to open it for writing
- -- unless we move the old one out of the way...
- let oldFile = filename ++ ".old"
- restore_on_error <- catch (renameFile filename oldFile >> return True) $
- \err -> do
- unless (isDoesNotExistError err) $ do
- hPutStrLn stderr (unwords ["Unable to rename", show filename,
- "to", show oldFile])
- ioError err
- return False
- (do hPutStrLn stdout "done."; io)
- `onException` do
- hPutStr stdout ("WARNING: an error was encountered while writing "
- ++ "the new configuration.\n")
- -- remove any partially complete new version:
- removeFile filename `catchIO` \_ -> return ()
- -- and attempt to restore the old one, if we had one:
- when restore_on_error $ do
- hPutStr stdout "Attempting to restore the old configuration... "
- do renameFile oldFile filename
- hPutStrLn stdout "done."
- `catchIO` \err -> hPutStrLn stdout ("Failed: " ++ show err)
- -- Note the above renameFile sometimes fails on Windows with
- -- "permission denied", I have no idea why --SDM.
-
-----------------------------------------------------------------------------
-- Sanity-check a new package config, and automatically build GHCi libs
-- if requested.
handler' e = Exception.throw e
#endif
+throwIOIO :: Exception.IOException -> IO a
+#if __GLASGOW_HASKELL__ >= 609
+throwIOIO = Exception.throwIO
+#else
+throwIOIO ioe = Exception.throwIO (Exception.IOException ioe)
+#endif
+
catchError :: IO a -> (String -> IO a) -> IO a
#if __GLASGOW_HASKELL__ >= 609
catchError io handler = io `Exception.catch` handler'
Exception.throw e
#endif
+
+-- copied from Cabal's Distribution.Simple.Utils, except that we want
+-- to use text files here, rather than binary files.
+writeFileAtomic :: FilePath -> String -> IO ()
+writeFileAtomic targetFile content = do
+ (tmpFile, tmpHandle) <- openTempFile targetDir template
+ do hPutStr tmpHandle content
+ hClose tmpHandle
+#if mingw32_HOST_OS || mingw32_TARGET_OS
+ renameFile tmpFile targetFile
+ -- If the targetFile exists then renameFile will fail
+ `catchIO` \err -> do
+ exists <- doesFileExist targetFile
+ if exists
+ then do removeFile targetFile
+ -- Big fat hairy race condition
+ renameFile tmpFile targetFile
+ -- If the removeFile succeeds and the renameFile fails
+ -- then we've lost the atomic property.
+ else throwIOIO err
+#else
+ renameFile tmpFile targetFile
+#endif
+ `onException` do hClose tmpHandle
+ removeFile tmpFile
+ where
+ template = targetName <.> "tmp"
+ targetDir | null targetDir_ = "."
+ | otherwise = targetDir_
+ --TODO: remove this when takeDirectory/splitFileName is fixed
+ -- to always return a valid dir
+ (targetDir_,targetName) = splitFileName targetFile